Characterization of Magnetic Field Distribution in a Trailing-Edge Shielded Head by Frequency-Modulated Magnetic Force Microscopy

In this paper, the ac magnetic field distribution of a trailing-edge shielded SPT head were successfully investigated by using a newly developed frequency-modulated magnetic force microscopy (FM-MFM) technique with a hard magnetic MFM tip. The results show sharper magnetic field gradient at the trailing edge than at the leading edge of the main pole. The perpendicular component of the magnetic field of the main pole region is opposite to that of the trailing shield/return pole region. As the write current increases, the saturation of magnetic field in the main pole region occurs from the trailing edge first. With increasing write current, the return field of the trailing shield edge increases significantly as well, which may cause return field-induced partial erasure. The double-peak feature of the distribution of ac magnetic field generated from the head only depends on the tip-sample distance and does not depend on the input write current. The FM-MFM technique used in this work was proved to be applicable in the imaging of the ac magnetic field of a recording head with high spatial resolution.